Possibly because all you have ever done here is post Show HNs. You haven't engaged in discussions outside of your own posts. You have not shared anything that was not your own work.
Hard to say for sure why people flag, but your history looks like someone who is using HN solely for their own personal benefit, not trying to be part of the community.
Sorry but is it still a promotion if I started an open source, have absolutely no commercial benefit from it and think it may be genuinely useful and helpful for people?
It's like telling linus torvalds to not talk about Linux because its "promotion" (not comparing myself or the scale but principally its exactly like that)
There doesn't have to be commercial gain for it to be promotion. The distinction is promotion vs contribution. If you view HN as a community and all you're doing is saying "look at the thing I made" rather than actively engaging with the community as a whole, then your contribution value to the community is low.
Hard to say for sure why people flag, but your history looks like someone who is using HN solely for their own personal benefit, not trying to be part of the community.
"Please don't use HN primarily for promotion"
It's like telling linus torvalds to not talk about Linux because its "promotion" (not comparing myself or the scale but principally its exactly like that)
Yes it is promotion.